A celebrity credit card promoted by NBA legend Magic Johnson — and backed by Goldman Sachs-turned-Hollywood movie mogul Steven Mnuchin’s OneWest Bank — has abruptly closed up shop after being sued for alleged trademark infringement, unfair competition and other charges by a competitor.

Entrepreneur Reed Wallace of Celebrity Cards International filed suit against Johnson and OneWest last year in a David vs. Goliath legal case in which he alleged he had a deal with Johnson to market and sell a prepaid “Magic Cash Card,” but that Johnson then “turned around and stuck a knife in my back” by striking a deal to instead launch a similar card with OneWest.

Johnson’s team failed to have the case dismissed. Then, Wallace’s legal team in January filed court documents asking to depose OneWest’s high-profile billionaire board members George Soros and Michael Dell.

But months later — after Wallace had told Page Six of the suit against Johnson and OneWest, “I’ve poured everything I had into this [venture], how can I have enough money to fight these billionaires?” — OneWest has suddenly shuttered its “Magic” prepaid card after a quiet legal settlement.

“We’re discontinuing our MAGIC program as of June 30, 2014, and all prepaid cards will be closed at that time,” the card’s site tells consumers, without any explanation as to why.

Mnuchin, a former top mortgage exec with Goldman Sachs, has made a splash in Hollywood by backing films, including the “X-Men,” “Alvin and the Chipmunks” and “Avatar” franchises, through his Dune Entertainment.

He recently partnered with director Brett Ratner and Australian billionaire James Packer to fund up to 75 movies in a blockbuster deal with Warner Bros.

Reps for Johnson and OneWest didn’t respond to a request for comment. Wallace’s lawyer Robert J. Hantman said, “Due to confidentiality, I can only say this case was settled to the mutual satisfaction of all parties.”